TWI Frequently asked questions
by Lee Ecclestone
Brazing is a joining process traditionally applied to metals (but also to ceramics) in which molten filler metal (the braze alloy) is drawn into, or retained between, the faying surfaces of the parts to be joined. In general, the melting point of the filler metal is above 450°C, but always below the melting temperature of the parent materials, which distinguishes the process from welding. The process can be undertaken in a variety of atmospheres including air, reducing, inert, or vacuum, and using a variety of heating sources such as torch, furnace, and induction coil.
To achieve a sound brazed joint, the filler and parent materials should be metallurgically compatible, and the joint design should incorporate a gap into which the molten braze filler can be drawn or distributed by capillary action. The required joint gap is dependent on many factors, including base material and braze alloy composition, and brazing atmosphere.
Brazing is a commercially accepted process, used in a wide range of industries, due to its flexibility and the high integrity to which joints may be produced. This makes it reliable in critical and non-critical applications, and it is one of the most widely used joining methods.
Further information
What are the different methods of brazing?
